From 59788a5caea5f292c86e07a31ee2b853d68db87e Mon Sep 17 00:00:00 2001
From: wangjian <wangjian161@huawei.com>
Date: Fri, 26 Mar 2021 11:21:16 +0800
Subject: [PATCH] node_device_udev: Serialize access to pci_get_strings)_

Since the functions provided by libpciaccess are not thread-safe,
when the udev-event and nodedev-init threads of libvirt call the
pci_get_strings function provided by libpaciaccess at the same
time the following can happen:

nodedev-init thread:
nodeStateInitializeEnumerate ->
  udevEnumerateDevices->
    udevProcessDeviceListEntry ->
      udevAddOneDevice ->
        udevGetDeviceDetails->
          udevProcessPCI ->
            udevTranslatePCIIds ->
              pci_get_strings -> (libpciaccess)
                find_device_name ->
                  populate_vendor ->
                    d = realloc( vend->devices, (vend->num_devices + 1), * sizeof( struct pci_device_leaf ) );
                    vend->num_devices++;

udev-event thread:
udevEventHandleThread ->
  udevHandleOneDevice ->
    udevAddOneDevice->
      udevGetDeviceDetails->
        udevProcessPCI ->
          udevTranslatePCIIds ->
            pci_get_strings -> (libpciaccess)
              find_device_name ->
                populate_vendor ->
                  d = realloc( vend->devices, (vend->num_devices + 1), * sizeof( struct pci_device_leaf ) );
                  vend->num_devices++;

Signed-off-by: WangJian <wangjian161@huawei.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/node_device/node_device_udev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 3f288589db..3daa5c90ad 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -331,6 +331,7 @@ udevGenerateDeviceName(struct udev_device *device,
     return 0;
 }
 
+static virMutex pciaccessMutex = VIR_MUTEX_INITIALIZER;
 
 static int
 udevTranslatePCIIds(unsigned int vendor,
@@ -349,12 +350,14 @@ udevTranslatePCIIds(unsigned int vendor,
     m.device_class_mask = 0;
     m.match_data = 0;
 
-    /* pci_get_strings returns void */
+    /* pci_get_strings returns void and unfortunately is not thread safe. */
+    virMutexLock(&pciaccessMutex);
     pci_get_strings(&m,
                     &device_name,
                     &vendor_name,
                     NULL,
                     NULL);
+    virMutexUnlock(&pciaccessMutex);
 
     *vendor_string = g_strdup(vendor_name);
     *product_string = g_strdup(device_name);